M&S says

Feel cool and comfortable while you work out with this women’s sports top, crafted to help you reach your fitness goals. No matter what your routine holds, breathability and lightweight fabric are essential, and this short sleeve sports top offers both. Finished off with moisture wicking and Quick Dry technologies, moisture is drawn away from the skin while you exercise. Team with your favourite leggings or shorts for a sports look perfect for any activity.

Care and Composition

35 days to return
You may return unused products within 35 days of purchase with a valid parcel summary document. Your items don't need to be in the original box or bag as long as they're securely packaged.How to return
It’s easy to return items to M&S. Simply print the returns label, attach it to the top of your parcel and insert the returns note in the parcel. Drop your parcel at a local post office. We will automatically deduct the cost of return from your refund.